N-protected synthesis method for use in making porphyrins

Abstract

One aspect of the present invention relates to a method of forming chemical compounds and, in particular, chemical intermediates having one or more pyrrole sub-units and at least one protecting group bonded to an atom within a pyrrole sub-unit. The method further involves removal of the protecting group so as to provide a desired chemical compound having one or more pyrrole sub-units. The method can be employed in making porphyrin compounds.

What is claimed is:  
     
       1. A method for preparing pyrromethene compound having at least two pyrrole sub-units, comprising: 
       a. reacting one or more N-protected pyrrole compounds with a pyrrole compound so as to provide a chemical intermediate having at least two pyrrole sub-units, and at least one N-protecting group bonded to the nitrogen atom of one of the pyrrole sub-units; and  
       b. deprotecting the chemical intermediate by removing one or more of the protecting groups from the chemical intermediate.  
     
     
       2. The method according to  claim 1 , wherein the chemical intermediate has two pyrrole sub-units. 
     
     
       3. The method according to  claim 1  wherein the chemical intermediate has three pyrrole sub-units. 
     
     
       4. The method according to  claim 3  wherein the chemical intermediate is a compound of formula:                    
       where R 1 , R 2 , R 3 , R 3 ′, R 4  and R 4 ′ are hydrogen or carbon-containing substituents and PG and PG′ are protecting groups. 
     
     
       5. The method according to  claim 1 , wherein step (a) comprises condensation of the pyrrole compounds. 
     
     
       6. The method according to  claim 1 , wherein the N-protecting group is BOC, MES, or TOS. 
     
     
       7. The method according to  claim 1 , wherein the N-protected pyrrole compound is a compound of the formula:                    
       where R 1 , R 2 , R 4 , R 5  and R 6  are hydrogen or carbon-containing substituents and PG is a protecting group. 
     
     
       8. The method according to  claim 1  wherein the chemical intermediate is a compound of the formula                    
       where R 1 , R 2 , R 3 , R 3 ′ and R 4  are hydrogen or carbon-containing substituents and PG is a protecting group. 
     
     
       9. The method of  claim 1 , wherein the chemical intermediate is a dipyrromethane. 
     
     
       10. The method of  claim 1 , wherein the chemical intermediate is a tripyrromethane. 
     
     
       11. The method of  claim 1 , wherein the chemical intermediate is a bilane, bilene, or biladiene.